Postdoctoral Research Fellows
Coastal Risks and Sea-Level Rise Research Group
Mark Schuerch is a coastal geographer. He started his studies in the Department of Geography at the University of Zuerich (Switzerland). After completing his first degree he moved to the Department of Geography at the Christian-Albrechts University of Kiel and completed his studies, specialising in Coastal Geography and Geographic Information Systems (GIS). For his diploma thesis he investigated the consequences of climate change on the Baltic Sea ecosystem. From April 2008 until July 2012, he completed his PhD thesis about the “Salt marsh development in a changing climate” in the research group “Coastal Risks and Sea-Level Rise” within the “Future Ocean” Excellence Cluster. Since November 2012, Mark continues working as Post-Doctoral Researcher in the research group “Coastal Risks and Sea-Level Rise” within the “Dangerous Ocean” arm (R06) of the “Future Ocean” Excellence Cluster in Kiel.
His research focus lies on the physical impacts of accelerated sea-level rise on coastal wetlands. These wetlands are important ecosystems and habitats for many red-listed plants and animals. In particular, he concentrates on the physical processes of sediment accretion on salt marshes and on the related processes in the foreshore of the salt marshes. By means of field measurements and numerical modelling he unravels the interactions between salt marshes and the tidal basins adjacent to these marshes.
Dr. Mark Schürch
Christian-Albrechts-Universität zu Kiel
+49 (0)431 880 1782
Mark is currently working on a project in the Rio de la Plata estuary in South America, where he and his colleagues investigate the relative influence of storm activity and changes of river discharge as a consequence of climate change and decadal climate variations (e.g. El Niño) on the long-term evolution of salt and freshwater marshes along the estuary.
Employing the numerical salt marsh accretion model that was specifically developed by Mark during his PhD project to incorporate the influence of changing storm patterns and changes in sediment supply on salt marsh accretion rates, this project aims to (i) improve our understanding of how salt and freshwater marshes in the Rio de la Plata estuary will develop in the future and (ii) expand our knowledge on how these marshes will react to increased rates of SLR under different storm and river discharge regimes.
For assessing the relative importance of the governing drivers, sediment characteristics and marsh accretion rates are analyzed at various locations along the estuary, using radiometric measurements, such as 210Pb. By employing the above mentioned numerical salt marsh model the separate influence of increasing storm activities and decadal variations of river discharges on marsh survival under various scenarios of SLR shall be quantified and estimations for the ability of the salt marshes to survive future SLR will be given. Additional field measurements are performed in the foreshore of the marsh in order to describe the local morphodynamics on the inter- and subtidal seafloor and to improve the estimations for sediment availability of the marshes fringing the Rio de la Plata estuary.
Within this study Mark and his colleagues specifically investigate the spatial patterns of salt marsh accretion rates on a salt marsh in the northern part of the North Frisian island of Foehr (in the German Wadden Sea). Radiometric datings are employed to derive historic sedimentation rates at various locations on the investigated salt marsh. In junction with additional field measurements on the prevailing flow conditions, the spatial distribution of suspended sediment, and the analysis of the present topographic and vegetation patterns on the marsh surface, the study will identify the most important driving factors for spatial patterns of accretion rates on salt marshes and their effects on how the marsh as a whole is capable to adapt to a rising sea level in the past and in the future.
Accretion processes on salt marshes are governed by various biological and physical parameters. Among the physical driving factors the inundation frequency and inundation height are thought to be the most important ones. Predicted sea-level rise (SLR) and a possible change of storm patterns might therefore impact the ability of salt marshes to survive predicted sea level rise. Historic accumulation rates on a barrier-connected salt marsh on the island of Sylt were estimated by means of 210Pb and 137Cs radioisotope analysis. Additionally, grain size analysis and measurements of organic carbon were conducted.
For the last 75 years accretion rates between 1 and 16mm year-1, showing strong variations and extremely high values in the years 1982 and 1992, were measured. Comparison of these sedimentation rates with historic tide gauge measurements at ‘Hoernum Hafen’, indicating the historic storm frequencies and storm intensities, shows that the growth of mature salt marshes is strongly dependent on both, storm frequency and storm intensity.
Global sea level rise and related changes of inundation frequencies and heights have been identified as an important driving factor for the development and the loss of coastal salt marshes all over the world. Various salt marsh models were developed and applied in the past in order to estimate the potential of salt marshes to survive future SLR. However, until now, the influence of changing storm patterns, as expected in many parts of the world, has largely been neglected in most of the existing salt marsh models. Within this project, we used an existing zero-dimensional salt marsh model and adapted it for integrating changing storm patterns and estimating how they would affect the ability of coastal salt marshes to survive projected SLR until the year 2100.
The performed model runs indicated that increasing storm activity, especially if trigged by an increase in storm frequency may increase the adaptability of salt marshes towards SLR by up to 3 mm yr-1, if a linear SLR scenarios is applied. For accelerating SLR scenarios, it was found that accelerating SLR is more likely to drown salt marshes than linear SLR scenarios, while, equivalent to the linear SLR scenarios, an increase of storm frequencies has the largest impact on increasing the adaptability of salt marshes to accelerating SLR.
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